Re: GDB 13.1 and clang

Chris Johns
2023-03-09T02:41:44Z

On 9/3/2023 7:53 am, John Baldwin wrote:
> On 3/8/23 1:22 PM, Chris Johns wrote:
>> On 9/3/2023 5:22 am, Simon Marchi wrote:
>>> On 3/8/23 15:07, Chris Johns wrote:
>>>> Hi,
>>>>
>>>> I have just tried to build the latest RTEMS tools and we now use gdb 13.1. I am
>>>> seeing a build failure on FreeBSD 13.1 of:
>>>>
>>>> In file included from ../../gdb-13.1/gdb/xml-tdesc.c:23:
>>>> In file included from ../../gdb-13.1/gdb/target.h:42:
>>>> In file included from ../../gdb-13.1/gdb/infrun.h:21:
>>>> In file included from ../../gdb-13.1/gdb/gdbthread.h:26:
>>>> In file included from ../../gdb-13.1/gdb/breakpoint.h:38:
>>>> ../../gdb-13.1/gdb/target/waitstatus.h:113:1: error: use of undeclared
>>>> identifier 'DIAGNOSTIC_ERROR_SWITCH'
>>>> DIAGNOSTIC_ERROR_SWITCH
>>>> ^
>>>>
>>>> I only have clang installed on the FreeBSD machine.
>>>>
>>>> A quick review of include/diagnostics.h seems to show support for
>>>> DIAGNOSTIC_ERROR_SWITCH only in the gcc area?
>>>
>>> Hmm, I see it in the clang section:
>>>
>>> # define DIAGNOSTIC_ERROR_SWITCH \
>>>    DIAGNOSTIC_ERROR ("-Wswitch")
>>>
>>
>> It seems I need to do a better review before posting :)
>>
>>> https://sourceware.org/cgit/binutils-gdb/tree/include/diagnostics.h?h=gdb-13.1-release&id=4f3e26ac6ee31f7bc4b04abd8bdb944e7f1fc5d2#n76
>>>
>>> Unless there's a typo I don't see.
>>>
>>> diagnostics.h is included at the top of waitstatus.h.  Is it possible
>>> that another unrelated diagnostics.h gets included on FreeBSD?  You
>>> could inspect the preprocessed file to see what the preprocessor
>>> included for diagnostics.h.
>>
>> There is another version installed here:
>>
>> $ pkg which /usr/local/include/diagnostics.h
>> /usr/local/include/diagnostics.h was installed by package binutils-2.37_2,1
>>
>> We have /usr/local/include early in the include list on FreeBSD to pick up some
>> of the required libraries installed as packages. I will check for a package
>> update or I revisit the build flags to see how it can be handled.
>>
>> Thank you for the prompt and helpful responses.
>
> Yes, I manually delete all the headers installed by binutils into
> /usr/local/include when building GDB from source locally to work
> around this. :(  I'm not sure of the best fix for this.

I am not sure why I have binutils installed on the box. I try to keep them clean
to make sure we have a base to test builds on. I suspect there is some skew in
the version binutils has and gdb now has.

> I tracked
> it down to the change to add zstd as ZSTD_CFLAGS is before BFD_CFLAGS
> in INTERNAL_CFLAGS_BASE in Makefile.in in this commit:
>
> commit 2cac01e3ffff74898c54fa5e6418817f5578adb6
> Author: Fangrui Song <maskray@google.com>
> Date:   Mon Sep 26 19:50:13 2022 -0700
>
>     binutils, gdb: support zstd compressed debug sections
>         PR29397 PR29563: Add new configure option --with-zstd which defaults to
>     auto.  If pkgconfig/libzstd.pc is found, define HAVE_ZSTD and support
>     zstd compressed debug sections for most tools.
>         * bfd: for addr2line, objdump --dwarf, gdb, etc
>     * gas: support --compress-debug-sections=zstd
>     * ld: support ELFCOMPRESS_ZSTD input and --compress-debug-sections=zstd
>     * objcopy: support ELFCOMPRESS_ZSTD input for
>       --decompress-debug-sections and --compress-debug-sections=zstd
>     * gdb: support ELFCOMPRESS_ZSTD input.  The bfd change references zstd
>       symbols, so gdb has to link against -lzstd in this patch.
>         If zstd is not supported, ELFCOMPRESS_ZSTD input triggers an error.  We
>     can avoid HAVE_ZSTD if binutils-gdb imports zstd/ like zlib/, but this
>     is too heavyweight, so don't do it for now.
>         ```
>     % ld/ld-new a.o
>     ld/ld-new: a.o: section .debug_abbrev is compressed with zstd, but BFD is
> not built with zstd support
>     ...
>         % ld/ld-new a.o --compress-debug-sections=zstd
>     ld/ld-new: --compress-debug-sections=zstd: ld is not built with zstd support
>         % binutils/objcopy --compress-debug-sections=zstd a.o b.o
>     binutils/objcopy: --compress-debug-sections=zstd: binutils is not built with
> zstd support
>         % binutils/objcopy b.o --decompress-debug-sections
>     binutils/objcopy: zstd.o: section .debug_abbrev is compressed with zstd, but
> BFD is not built with zstd support
>     ...
>     ```
>
> I have not tried moving ZSTD_CFLAGS after BFD_CFLAGS, but if it worked I
> think the right solution is to ensure all the "local" includes for things
> in git come first before any includes that pull from the installed system.
> I think this would mean moving READLINE_CFLAGS (for systems that use a
> system readline), ZLIBINC, and ZSTD_CFLAGS after INCLUDE_CFLAGS.

Ah OK.

> I just tried this and it worked for me locally:
>
> diff --git a/gdb/Makefile.in b/gdb/Makefile.in
> index 6e39383eb93..40497541880 100644
> --- a/gdb/Makefile.in
> +++ b/gdb/Makefile.in
> @@ -629,8 +629,8 @@ INTERNAL_CPPFLAGS = $(CPPFLAGS) @GUILE_CPPFLAGS@
> @PYTHON_CPPFLAGS@ \
>  # INTERNAL_CFLAGS is the aggregate of all other *CFLAGS macros.
>  INTERNAL_CFLAGS_BASE = \
>      $(GLOBAL_CFLAGS) $(PROFILE_CFLAGS) \
> -    $(GDB_CFLAGS) $(OPCODES_CFLAGS) $(READLINE_CFLAGS) $(ZLIBINC) \
> -    $(ZSTD_CFLAGS) $(BFD_CFLAGS) $(INCLUDE_CFLAGS) $(LIBDECNUMBER_CFLAGS) \
> +    $(GDB_CFLAGS) $(OPCODES_CFLAGS) $(BFD_CFLAGS) $(INCLUDE_CFLAGS) \
> +    $(READLINE_CFLAGS) $(ZLIBINC) $(ZSTD_CFLAGS) $(LIBDECNUMBER_CFLAGS) \
>      $(INTL_CFLAGS) $(INCGNU) $(INCSUPPORT) $(LIBBACKTRACE_INC) \
>      $(ENABLE_CFLAGS) $(INTERNAL_CPPFLAGS) $(SRCHIGH_CFLAGS) \
>      $(TOP_CFLAGS) $(PTHREAD_CFLAGS) $(DEBUGINFOD_CFLAGS) $(GMPINC) \

This worked, thanks. I will add it as a patch when building on FreeBSD and
remove it if this makes it into 13.2 or the development branch.

Again thanks
Chris